Looks very similar to a scaffolding collapse in El Paso Texas back in the 1980's - high scaffolding holding up a cast-in-place bridge deck.
The scaffolding used a nested column system (pipe within a pipe) and the contractor had shoved short pieces of #3 rebar into the side holes to serve as shear pins instead of the required high strength steel pins. Rebar sheared off during the deck placement and several workers died.
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